Forewarning: I don't know that much about electrical terms, so please excuse any mistakes I've possibly made.

I recently moved the TV in my living room and ran a new line for the electricity to the TV. In doing so, I discovered that I had to turn off TWO breaker switches to kill the power to the area I was working in. If either breaker is still on, all devices in the area still have power.

On top of that, there is a large and varying array of equipment plugged into these two breakers.

All outlets in living room (TV, stereo receiver, computer, XBOX, Wii)

All recessed lighting in living room

Refrigerator

Microwave

Air compressor in garage

Clothes washer in garage

How is it that these breakers can be connected, and is it OK/safe that all this stuff is connected to a line that is coupled like that? I have been in the house for almost a year and never had any issues with the circuit tripping.

The breakers are both 20A switches. In the picture, they are right below the 100A switch on the top right.

UPDATE: I removed the front panel from the breaker box and took some pictures.

UPDATE 2: found out that the clothes washer is also on this circuit

UPDATE 3: I've checked about half of the outlets and haven't found the break yet. I'll continue tomorrow.

Are you saying that there's an outlet that only turns off when both breakers are turned off?
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Jay BazuziSep 1 '11 at 2:23

3

Turn off the main breaker, remove the front panel, take a photograph of the wiring on those 2 breakers, and post the picture here.
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Jay BazuziSep 1 '11 at 2:25

2

It sounds like there are two branch circuits hooked together, but it could be at any point along the circuit. Get yourself a continuity tester if you don't already have one.
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Niall C.♦Sep 1 '11 at 2:38

8

If you remove the front panel, remember that the terminals where the incoming service wires connect are still hot even when the main breaker is off!
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JayLSep 1 '11 at 3:15

@Jay yes, there are many, many outlets that only turn off when both breakers are off
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Jeremy WhiteSep 1 '11 at 4:18

7 Answers
7

Unraveling this mess may be difficult. Seeing the 30 amp breaker join the two sides indicates that the two hot lines go straight down each side in the back of the panel rather than alternating every other breaker. If it were alternating, then any 220 circuit only needs two vertical slots rather than taking up all the space of both sides as well. What this means is that these two circuits can be joined anywhere since the lines are in phase with each other.

The easy fix is if you have an incorrect connection in that breaker panel, rather than each line going its separate way. If that's the case, you remove the connection and the problem is solved. So as others say, the first step is the open it up and take a photo (with the power off and being careful to avoid the lines feeding the main breaker).

The difficult fix is if the connection is somewhere else in the house. Unless you know how the home is wired, you are left with breaking the connection at various points until you find the location that roughly splits the circuit in half. To do this, you open up an outlet in one of the rooms, disconnect the load side of the outlet (pick a side if you don't know which is which), and see if only half the outlets turn on when you reset one breaker. Try to make the split in the circuit between two rooms.

Once you decide where to split the circuit, you're left with an extra wire from the other circuit in the J box to cap or remove. The proper solution would be to remove it, but doing so will likely require opening up the wall. If you cap it, make sure each wire cannot touch anything else to avoid the risk of a short, and then label the wire so no one hooks it back up in the future. I would also go through the extra effort to find the other side of this connection and disconnect it and label it on both sides.

Edit: Seeing the separate red and black wires makes me wonder if they continue through each outlet with two circuits like mgb suggests. If so you just need to locate where the two lines cross. If the two circuits are separated in the outlets themselves, then it should be obvious when you open an outlet up and see a red and black going to the separated top and bottom. In that case, turn the power off to both circuits, disconnect an outlet, cover the exposed connections, and turn the power on to only one circuit. If you now have two separate circuits, then then crossed connection is in the outlet you disconnected or one of the dead outlets in the home. If the circuits are still joined, then the problem is in one of the live outlets. Use the process of elimination to avoid opening too many outlets.

As always, when working with electricity, ensure the power is off before you risk anything touching a wire. Test ever wire in the outlet before beginning work, especially in your situation. And when you open the panel, the line side of the main breaker is still hot even when that breaker is shutoff. If you feel nervous about doing any of this yourself, then hire an electrician.

That was the first thing that I checked. But none of the devices I mentioned turn off unless BOTH switches are flipped.
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Jeremy WhiteSep 1 '11 at 4:19

1

that's what mgb is saying...if there is a short connecting the circuits, then as long as one of the two is on, it might be powering both circuits. It could be that one of the outlets itself was wired incorrectly and is the cause of the two circuits 'overlapping'.
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DA01Sep 1 '11 at 6:23

If that is the case, then I'll delete my request that you clarify your question and do more testing. You really are going to have to take the cover off the service panel. (Was trying avoid it for safety reasons.) The panel must be too old to have alternating +/-120V busses, and I suspect this was done intentionally in order to make the breakers less sensitive. One of them was probably tripping, and instead of buying a new 30A breaker or something like that, they just tied two together, putting everything on a 40A circuit. In any case, this is quite awkward. Against code, obviously.
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MichaelSep 1 '11 at 9:23

1

This is common? I've always thought that two circuits in the same J box was quite unusual, if not against code for this very reason. The only time the top and bottom outlet should be different is for a switched outlet, but still on the same circuit.
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BMitch♦Sep 1 '11 at 12:20

9

A split outlet with two circuits may have been replaced without removing the metal tab that separates the two halves.
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TomGSep 2 '11 at 11:39

Take a look at this web page, paying attention to the part where they break off the tab/jumper in order to keep the two circuits separate, and then, in your home, search the receptacles on the two circuits for one or more receptacles that have two hot wires coming in, and the tab/jumper still attached.

Wouldn't that mean that when both breakers are on, we'd have a short between the two legs? This would either blow breakers or make the monthly electric bill absurdly high.
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Chris CudmoreApr 18 '13 at 12:58

If the two breakers are on the same hot leg, there would be no short. If they were on opposite legs, yes, you'd have a dead short and one or both breakers would trip.
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TomGApr 21 '13 at 0:36

I've seen situations where two circuts are run to the same junction box, and then split off from there. In modern wiring both hot wires would share the neutral wire.

A mis-wiring in the junction box could join both breakers together, causing the need to flip both breakers to disable the power to the lights and applicances. This is just like the mis-wired split outlet that has two feeds mentioned earlier.

You are going to need to open up the boxes and figure out where the problem is.

I'd look in the service panel and check the receptacles first to make sure the jumpers were removed (I'd guess the possibility that this is a case of a failure to remove the jumper is about 40-50%.) You might be right, but I'd say that finding and looking in the jboxes is the biggest PITA and the least likely to be the culprit.
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MichaelSep 2 '11 at 21:16

any chance one of these junction boxes could be a sealed box in the attic/wall, rather than an outlet or switch?
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Jeremy WhiteSep 3 '11 at 2:36

1

Jeremy, it is possible the mis-wired junction box is in the attic, but probably more likely it is in an outlet or switch that a previous homeowner or handyman touched.
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Scott BrunsSep 6 '11 at 15:24

Very simple answer here. If 2 breakers are controlling the same device in a residential setting, it's wired WRONG. Shut everything off and call for professional help. The only time 2 breakers can feed the same thing is if there is a device called a TIE BREAKER in place. This will never be the situation in a residential setting. TIE BREAKERS only exist in buildings where a certain machine needs a constant (or almost constant) power supply. A TIE BREAKER will decide which power supply is constant and it will shut off the alternate power supply.

What would such a device look like? The previous owner was a do-it-yourselfer and messed of a lot of things in the house. I wouldn't put it past him to use something like that.
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Jeremy WhiteApr 18 '13 at 20:47

Something not mentioned above: since two 20A breakers are tied together, you effectively have a 40A breaker. An overload of say 35A wouldn't trip the breakers, but could easily overheat the wiring and start a fire. Resolution is not mentioned above, hope it was corrected before a disaster.